Rough Start On Start Up (hesitation)

jarettg · March 31, 2011

the past few weeks i have started my truck (parked in the garage in 0 degree celcius weather) turning over fine, and then the RPM's are very low for 1-2 seconds almost like its going to stall. after that the RPM's go up as ususal.

today i put it in reverse about 10 seconds after starting it and the RPM's dropped almost to 0 again (leaving enging very quiet) for a few seconds, and then the RPM's went up again. very weird.

its almost like the engine isnt getting enough fuel or air into the engine, but it drives fine after start up. it may be the fuel pump.

i put new oil in about 5 weeks ago, which i dont think is an issue becuase it has been running fine with the exception of the past 2 weeks.

does anyone have any idea or suggestion? my truck is still on warranty and i will call them to set up and appointment. 6 times in the past 3 months.

hoochi · March 31, 2011

the past few weeks i have started my truck (parked in the garage in 0 degree celcius weather) turning over fine, and then the RPM's are very low for 1-2 seconds almost like its going to stall. after that the RPM's go up as ususal.

today i put it in reverse about 10 seconds after starting it and the RPM's dropped almost to 0 again (leaving enging very quiet) for a few seconds, and then the RPM's went up again. very weird.

its almost like the engine isnt getting enough fuel or air into the engine, but it drives fine after start up. it may be the fuel pump.

i put new oil in about 5 weeks ago, which i dont think is an issue becuase it has been running fine with the exception of the past 2 weeks.

does anyone have any idea or suggestion? my truck is still on warranty and i will call them to set up and appointment. 6 times in the past 3 months.

My Denali did that before the fuel pump failed try changing your fuel filter first.

Z45 · March 31, 2011

I noticed this with my 2010 5.3L this spring with only 9,500 miles. It might be fuel because for the last week its not been doing it and I been fueling at a different place in that time.

jarettg · March 31, 2011

ill have the dealership look at it, thats what warranty is for

i dont think it is the fuel i have been buying gas from the same pumps for the past few months

hoochi · March 31, 2011

Try fuel filter then if that doesn't work it might be fuel pump, that is what my Deanali did before the pump went out.

MaverickZ71 · March 31, 2011

You might try running a bottle or two of Heet Fuel Treatment (in case you've got some water in the gas) or Techron Fuel System cleaner in it. As far as I know, the new 5.3L flex fuel engines do not have an owner-serviceable fuel filter.

scani6 · April 6, 2011

We experienced the same problem on our 2008. Took it to the dealership (under warranty), and they replaced the throttle body and cleaned the injectors. That solved our problem. I wouldn't even want to guess how much that would have cost out of pocket.

AThomas7782 · April 6, 2011

Try fuel filter then if that doesn't work it might be fuel pump, that is what my Deanali did before the pump went out.

No serviceable fuel filter on GMT900s.

ljburns · April 6, 2011

I had the same problem a few months ago. I also was purchasing gas from the same place. I added two bottles of the STP fuel treatment and switched gas stations. Havent had any problems since I burned thru the tank of gas with the treatment.

jarettg · April 6, 2011

yesterday it wouldnt start the first time i tried starting it, and the second time it started very rough. oh and a lovely blue exhaust cloud came out of the exhaust pipe when it did start.

this morning the check engine light came on. i called gm and it is booked in for next week.

this POS vehicle is starting to fall apart on me...not very impressed...

jarettg · April 12, 2011

just got back from the dealership, they stated that the fuel trim was out of wack. they stated that when fueling i should wait 20 minutes before parking it so that the engine can calculate how much alcohol is in the fuel. he said this could have been caused by a bad batch of gas or whatever.

i have been buying the same 89 octane gas from shell for the past 6-8 months.

it is fixed now and it starts up fine. will be a matter of time before i have it in the shop again though...

Shatterz · April 12, 2011

just got back from the dealership, they stated that the fuel trim was out of wack. they stated that when fueling i should wait 20 minutes before parking it so that the engine can calculate how much alcohol is in the fuel. he said this could have been caused by a bad batch of gas or whatever.

i have been buying the same 89 octane gas from shell for the past 6-8 months.

it is fixed now and it starts up fine. will be a matter of time before i have it in the shop again though...

I would call them out on the wait 20 minutes deal (so everytime you get fuel you have to drive or let the engine run for 20 minutes??????????? . That sounds like they really don't know what's going on or the true cause of your problems.

05GMCZ71 · April 12, 2011

Get another truck.

SouthCo · April 12, 2011

Yeah, I fill up down the street from my house. I can't idle for 20. All of our trucks would being doing that if you had to wait 20 minutes everytime you fill up before shutting her down. Hope your issue doesn't resurface.